Electric fuse



1,439,870 F. N, CGNANT. ELECTRIC FusE. FILED JUNE l, 1920.` 2SHEETS-SHEET 2 Patented Dec. 26, 1922.

UNITED STATES PATENT 'QFFlCBj FRANKLIN N. CONANT, OF NEWBUBYPORT,MASSACHUSETTS, ASSIGNOR, yBY MESNE ASSIGNMENTS, TO THE CHASE-SHAWMUTCOMPANY, A. CORPORATION F MASSA- CHUSETTS.

'ELECTRIC rusa.

Application led June 1,

To all whom it may concern:

Be it known that I, FRANKLIN N. CONANT, a citizen of the United States,residing at Newburyport, in the county of Essex and State ofMassachusetts, have invented an Improvement in Electric Fuses, of whichthe following is a specification.

This invention relates y to electric fuses and has particular referenceto enclosed fuses of the cartridge type although valuable for openfuses, and has for its object to improve the construction and operationof such, fuses. Fig. 1 is a side elevation of a renewable electricfuseof the cartridge type in which my invention is incorporated.

Fig. 2 is a sectional longitudinal elevation of the fuse of Fig. 1.A

Fig. 3 is aplan view of the current-carrying elements of the fuse.

Figs. i and 5 are end views of the left'and right end caps respectivelyof the fuse.

Fig. 6 is a plan View of a fuses-locking plate. l

Fig. 7 is a side view of the plate of Fig. 6.

Fig. 8 is a plan View of apressure plate.

Fig. 9 is a plan view of a packing disc.

Fig. 1() is a side elevation, partly broken away of a modified form ofrenewable electric fuse embodying my invention.

Fi 1l is a sectional detail of an end of the use illustrating onearrangement for connecting the fusible element to the end ferrule.

Fig. 12 is an end view of Fig. 11,

Fig. 13 is a plan View of a fuse-locking plate employed in themodification illustrated in Fig. l0.

Fig. 14 is a sectional detail illustrating a modified arrangement bywhich the fusible 40 element is connected with the end ferrule.

Figs. 15 and 16 are plan and side views respectively of a modified formof fusible element.

As here shown, the fuse with which my 45 invention is associatedincludes the tubular casing 10 of insulating material, as fibre, havingthe end-ferrules 11 and 12 secured thereon by suitable means. Saidend-ferrules are formed with the screw-threaded 50 side-walls 13 adaptedto removablypreceive end-caps, and the end-walls 14 and 15. Saidend-walls are formed with the centrally disposed more-or less circularapertures 16 and 17 therein having the opposed fuse-terminal le20.serial no. assale.

receiving slots 18. It will noted that the aperture 17 in ,theright-hand end-ferrulc is larger thanthe aperture 16 in the left-handtween the bottom of the l'opposed slots 18, in

both end-ferrules is the ksamey however.

The fusible element is carried by the rigid strip 19 of insulatingmaterial comprising a fuse holder. y comprising copper plates 20 arefixed by the bolts 21 to opposite faces of said insulating strip andsaid terminals have their inner and rstrip-engaging end-portions 20slightly reflexed whereby to admit of said terminals being in axialalignment in the enclosing casing. Said 'terminals 20 are formed withthe opposed notches 22 therein adapted to engage the end-walls of theend-ferrules for centering .and maintaining them in correct position inthe fuse casing.

The fusible element preferably comprises the separate flat fuse strips23 each having the oblong perforations 24 providing the strips withcentral readily fusible portions of similar resistance. These aresecured at one end to the fuse terminals 20 by said bolts 21 andextended toward each other on opposite sides of said insulating strip19. A relatively massive bolt 25, preferably of copper, 1s extendedthrough said strip and is held in place by a relatively massive nut 25a;also preferably of copper, Whereb electrically -to connect -the ends ofsai fuse strips in series with the fuse terminals and secure the endsthereof to the insulating strip 19. Relatively massive Washers 26 alsopreferably of copper, disposed over said boltbetween said fuse stripsand insulating strip serve tol support said fuse strips above and freefrom contact with said insulating stri The fusible element thusconnected forms in effect two fuses in series connected by permanentcontact posts which are, in eect, intermediary terminals and are, inpractice, infusible with the portion of the fusible elements between thereadily fusible portions supported. The current-carrying components ofthe fuse are thus united in a unitary structure by this arrangementwhich can be sold as a separate article of 'manuq Knife-blade fuseterminals;

facture from which the knife blade terminals may be omitted.

In assembling 'the fuse, the unitary structure formed by the strip 19with assembled fuse strip and fuse ter1ninals,is inserted through theaperture in the end-wall of the right-hand end-ferrule, and the slots inthe fuse terminals are brought into alignment with theend-walls of saidend-ferrules, the fuse-terminals are then angularly` rotated aboutninety degrees, causing the end-walls to enter the slots in saidterminals, thereby locking the structure against axial. displacement.Locking-plates, comprising the-discs having the vcentral elongatedl slot31 formed with the struck-out flanges 32 and tlie'opposed ears 33 struckout and reflexed from the periphery of the disc, are slipped over thefuse terminals and the ears 33 enter the slots in the end-walls, therebylocking thefuse terminals against rotation. Packing washers comprisingthe 'discs 34 formed of leather or other soft and flexible materialhaving the elongated slots 35 therein are received on the fuse terminalsand bear against the locking plates'30; and the slots in said discsaresuch that the discs snugly l`engage t/he terminals to prevent escapekof gas therebetween. Pressure plates `36.having the terminal-receivinglslots 37 therein are placed 0n the terminals and the interiorlythreaded end-caps 38 are, then screwed on the end-ferrules thereblocking the fuse elements in position. T e side Walls of thev end-capsmay be provided with perforations 40 therein to admit of the expu sionof gas from 4the fuse casing upon the blowing of the fuse.

Whereas l have above set forth a renewable fuse of the cartridge typehaving .knife- Iblade terminal-portions, in which my invention isembodied, yet the invention is applicable to other t pes of fuses, andin Figs. 10 through 16, Iyhave illustrated the invention embodied inanother type of fuse,` and specifically, in a renewable fuse havingendcaps by which the fuse is connected to an electric circuit instead ofby the knife-bladeI terminals.

In thismodification, theY fusible elements, comprising the fusiblestrips 23 and the insulating supporting bar 19, may be as before, andthe relatively infiexible knife-blade fuse terminals 20 are replaced bythe relativel thin conducting terminal-portions admitting of beingreflexed over the locking plate 51 in the manner illustrated in Figs.l() and l1.

The locking plate 51 comprises a disc similar to the plate 30 of Fig. 6,having the locking ears 52 adapted to enter the slots 18 in the endfermle 12 and the central slot through which the terminal-portion 50 isadapted to be extended. The end-caps 53, in this modification, havingthe solid enclwall 53a is received over the end ferrule and compressestheJ refiexed portion of the terminal between the locking-plate and itsendwall thereby firmly securing the terminal in place and providing agood electrical contact between it and the end-cap.

In the modification illustrated in Fig. 14:, the fuse terminals 54 arevery similar to vthe terminals illustrated in Figs. 1, 2 and 3 with thedifference that the slots 22 are omitted and are shortened in length sothat they but slightly protrude beyond the locking-plates 30 when thefusible element is in place within the enclosing tube. The end caps 53aengage the` protruding ends between them and thereby lock the fusibleele-ment and the locking-plates in place.

A. modified form of fusible element which embodies some of. the featuresincorporated inthe fusible element illustrated infFigs. 2y and 3, isillustrated in Figs. 15 and 16.

Instead of forming the fusible element` of a plurality of separatefusible strips, each having one or more readily fusible portions, andconnecting all of the strips in Series between the fuse-terminals, l mayhereincutilize a single fuse stripl having a plurality of' more readilyfusible portions 55 separated by the less readily fusible portions 56and secure the whole or part of the less readily fusible portions 56 tothe insulating bar or strip 19a by the bolts 57- For some purposes thisconstruction may be'used instead of that above set forth.

l claim:

1. An enclosed electric fuse of the cartridge type comprising a singletubular enclosing casing,- and a plurality of rfusible elements ofsimilar resistance arranged therein in series.

2. An enclosed electric fuse of the cartridge type comprising a. singletubular enclosing casing, knife-blade terminals extended froni the endsthereof, and a plurality of fusible elements of similar resistancearranged within said casing connected in series between said terminals.

3. A renewable electric fuse of the cartridge type comprising a tubularenclosing casing, end caps removably arranged on the ends of saidcasing, and a lplurality of fusible elements of similar resistancearranged within said casing connected in series between said end caps.

1. A renewable electric fuse of the cartridge type comprising a tubularenclosing casing, end caps removably arranged on the ends of saidcasing, knife-blade terminals detachably extendedfrom said end caps, anda plurality of fusible elements of similar resistance arranged wit-hinsaid casing connected in series between said terminals.

5. A renewable electric fuse of the `cartridge type comprising anenclosing casing,

end-caps removably arranged thereon, knitei lllll blade terminalsdetachably extendedfrom` Astrip arrangedwithin sald casing connectingsaid terminals, and a plurality of fusible elements supported by saidstrip connected in series between said terminals.

6.l A renewable electric fuseof the cartridge type comprising anenclosing casing, end-caps removably arranged thereon, fuse terminalsremovably supported by said endcaps, a fuse-supporting insulating stripar ranged within said casing supporting said terminals at its ends, anda plurality of fusible elements carried by said strip on opposite sidesthereof connected in series with said terminals.

7.- A renewable electric' fuse of the cartridge type comprising anenclosing casing, end-caps removably arranged thereon, fuse terminalsremovably supported by said end-4 caps, a fuse-supporting insultaingstrip arranged within said casing supporting said terminals at its ends,a -plurality "of fusible sides thereof electrically connected with saidterminals, and means extended through said strip electrically connectingsaid fusible elements.

8. In an electric fuse oaf-k the cartridge type,.a fuse holdercomprising a fuse-supporting strip of insulating material, .fuseterminals secured to the ends of said strip, a plurality of fusibleelements of similar resistance supported by said strip and connectedwith said terminals, and means having high melting point and lowresistance electrically connecting said fusible elements 1n series.

9. A fuse holder/for a renewable electric fuse of the cartridge typecomprising a fusesupporting strip of insulating material, fuse terminalssecured to the ends thereof, and a fusible element having a plurality ofmore readily fusible portions of similar resista-nce in series connectedto said strip in electrical connection with said terminals.

1'0. An electric fuse of the cartridge type comprising an enclosingcasing,'fuse terminals carried by the ends thereof, a fusible elementlarranged within said casing elecA trically connected with saidterminals, said fusible element having a plurality of more readilyfusible portions of similar resistance in series, and means engageablewith said fusible element between said more readily fusible portions tosupport and hold it. y

11. A fuse link, consisting of a strip of insulating supportingmaterlal, and a current carrying element, consisting of strips ofreadily fusible material of similar resistance, centrally connected tosaid supporting material byv connections of vhigh melting point and lowresistance compared to the 'fusible element, which connections alsoserve elements carried by said strip on oppositer to electricallyconnect said fusible elements in series. v

. 12. A fuse link, consisting of a strip of insulating s upportingmaterial.,V and a current carrying element, consistlng of strips ofreadily fusible material of similar resistance, carried by said strip onopposite sides thereof, centrally connected electrically to each other bv material of high melting point and low resistance compared to thefusible element, said connections passing through said supporting stripand connecting the same firmly to the supporting material in series.

In testimony whereof, I have signed my name to this specification.

FRANKLIN N. CONANT.

